Accident Bell 47G-3B-1 N999DW,
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ASN Wikibase Occurrence # 297182
 
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Date:Saturday 8 June 2002
Time:09:30 LT
Type:Silhouette image of generic B47G model; specific model in this crash may look slightly different    
Bell 47G-3B-1
Owner/operator:Private
Registration: N999DW
MSN: 6604
Year of manufacture:1967
Total airframe hrs:4123 hours
Engine model:Lycoming TVO-435-D1B
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Nederland, Colorado -   United States of America
Phase: Unknown
Nature:Private
Departure airport:Nederland, CO
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
Prior to the flight in mountainous terrain, the pilot obtained a weather forecast that called for winds from the southwest at 30 mph, with gusts up to 40 mph. The flight departed and was in cruise flight at 9,000 feet (700 feet agl) with a 20-25 knot headwind and experiencing light turbulence, when the flight encountered "severe turbulence." The pilot stated that the helicopter went "up and down violently for a period of 2-3 seconds." The tailrotor drive shaft was severed by the main rotor blades, and the helicopter then experienced "a right yaw that full application of left pedal would not correct." The pilot stated that during the event the engine and rotor rpm increased past their upper limits. He was able to bring the engine and rotor rpm within limits and regained control of the helicopter. Subsequently, the pilot performed an autorotation to sloping terrain without further incident. According to a witness, who was fishing on a lake 4 miles from the accident site, he observed water spouts between 2 and 8 feet tall and high swirling winds near the time of the accident.

Probable Cause: the pilot's inadvertent in-flight encounter with severe turbulence, which resulted in main rotor-tailboom contact and the separation of the tailrotor drive shaft.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: FTW02LA177
Status: Investigation completed
Duration: 9 months
Download report: Final report

Sources:

NTSB FTW02LA177

Revision history:

Date/timeContributorUpdates
14-Oct-2022 15:27 ASN Update Bot Added

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